RESEARCH ON PREDICTION OF DEBRIS FLOWS AND DEVELOPMENT OF THE DISASTER PREVENTION SYSTEM

山樱岛是日本最活跃的火山，在过去的十年里，它因火山灰和泥石流而造成了严重的破坏。本研究的目的是探讨一种预测方法，为该地区的降尘和降雨泥石流灾害的防治提供理论依据.得到了火山灰沉积深度与LANDSAT-4卫星MSS图像强度的关系。观察到的晶粒尺寸分布与理论计算相吻合。根据火山喷发高度、火山口周围积灰率和上层风向频率等资料，推导出火山灰喷发量的新计算方法。每一次火山灰喷发，在过去的十年里，数量可以计算在四万吨左右。1985年火山灰年喷发量达3000万吨。为分析发生条件， ...更多信息 对于长濑河泥石流，如果累积降雨量超过7 mm，则可能发生泥石流，超过13 mm肯定会发生泥石流。实验室新沉积灰的实验数据证实了这一结果。同时，通过计算实验，得到了考虑堆积灰分布和坡长分布的泥石流外流模型，该模型可普遍应用于天山泥石流灾害的防治。樱岛。鹿儿岛县的公共事务所每天都可以获得建设省所属国宫山雷达雨量计的图像数据。1986年6月，鹿儿岛市遭遇强降雨，滑坡的水平面分布与雷达测雨仪测得的降水强度相吻合。此外，我们检查了泥石流的发生在山。结合樱岛的降水强度，其发生概率的结果对泥石流的预报有一定的参考价值。少

Mt. Sakurajima is the most active volcano in Japan, it has been providing serious damages in these last ten years by ashfall and debris flows. The purposes of this study are to investigate a predicting method of debris flows caused by heavy ashfall and rainfall and to establish a fundamental theory to reduce these disasters in this area.1. A relation between depth of deposited ash and an intensity of MSS-image by LANDASAT-4 is obtained. Observed distributions of the grain size coincide with theoretically calculated ones. A new calculating method of an amount of erupted ash was deduced from data of the eruption height, the rate of deposited ash around the crater and frequency of a wind direction in an upper layer. Every time ash is erupted, the amount can be calculated at about forty thousand tons in these last ten years. And it has attained to seventy thousand tons, and an annual amount of erupted ash reached into thirty million tons in 1985.2. For an analysis of occurrence condition o … More f debris flow in the Hase River, if the cumulative rainfall exceeds 7 mm, occurrence of debris flow is possible and an excess of 13 mm would certainly cause an occurrence. This result was confirmed by experimental data of newly deposited ash in a laboratory. Meanwhile, a model of outflow of debris was also obtained by computational experiments, considering distributions of deposited ash and of slope length, and it can be generally applied to the disaster prevention in Mt. Sakurajima.3. Image data by a radar hyetometer at Kunimiyama, which belongs to the Ministry of Construction, is daily obtainable at public offices in Kagoshima Prefecture. In June 1986, a heavy rainfall attacked Kagoshima City, and a horizontal plane distribution of slope collapses coincided with the intensity of precipitation by the radar hyetometer. Furthermore, we checked for occurrence of debris flow in Mt. Sakurajima with the intensity of precipitation, the result for probability of occurrence is useful to forecast for debris flows. Less